Overview of adj day-by-day

The adj day-by-day has 1 sense

• daily, day-to-day, day-by-day, day-after-day -- (of or belonging to or occurring every day; "daily routine"; "a daily paper")

Overview of adv day-by-day

The adv day by day has 1 sense

• day by day, daily -- (gradually and progressively; "his health weakened day by day")